The present invention relates to a ceramic disc valve cartridge for faucets, spigots, taps, or the like, and more particularly to such a valve cartridge including a force-fit retainer which holds the ceramic discs in said valve.
Valve cartridges are known which use a rotating ceramic disc and a fixed ceramic disc adjacent one another to control the flow of fluids through the cartridge. The rotating and fixed ceramic discs have apertures therethrough such that the rotating disc moves between a fully closed position wherein the rotating disc completely blocks the apertures in the fixed disc and a fully open position wherein apertures in both discs are fully aligned. Additionally, the rotating disc may assume any position between the fully blocking and fully aligned positions which allows the user to adjust fluid flow through the cartridge. The contacting surfaces of the fixed and ceramic discs are manufactured to a tolerance that prevents water passing therebetween. An advantage of the ceramic discs is that they do not require a large number of turns in order to move between the completely open and the completely closed positions. Additionally, such ceramic disc valves do not drip and last substantially longer than conventional gasket valves.
Valve cartridges are also known which include two ceramic discs secured within the valve body by a retainer. One such retainer is illustrated in U.S. Pat. No. 3,807,455 to Farrell which shows a valve body and retainer which are made from plastic. The valve body and retainer are held together by ultrasonic welding. However, plastic parts do not have sufficiently stable properties for long term durability. Additionally, ultrasonic welding increases the steps required to assemble the valve and may alter the body or retainer shape during welding.
Other prior art retainers are illustrated in U.S. Pat. No. 3,881,570 to Ziebach et al. and U.S. Pat. No. 3,831,621 to Anthony et al. Both of these retainers are received on the end of the valve body and held in a channel circumscribing the inside of the valve body. However, providing a circumscribing channel on the inside of the valve body makes manufacturing of the valve body difficult. Further, the retainers of Ziebach et al. and Anthony et al. only support two sides of a sealing gasket adjacent the inlet end of the valve cartridge and thus do not provide sufficient support for an O-ring.
U.S. Pat. No. 4,331,176 to Parkinson shows a valve cartridge including ceramic discs and a tail piece which is received within the valve assembly body. However, the tail piece includes a projection received within the fixed ceramic disc, and the tail piece exerts a force on the ceramic discs which varies. Thus, the tail piece may exert too much force on the ceramic disc which substantially reduces the life of the valve discs or increase the force required to rotate the ceramic discs. On the other hand, the tail piece may not exert sufficient force on an O-ring positioned between the tail piece and the fixed ceramic disc for the O-ring to provide a fluid seal.
U.S. Pat. No. 4,821,765 to Iqbal et al. and U.S. Pat. No. 4,651,770 to Denham et al. show valve cartridges including ceramic discs and having gaskets which secure the discs in the cartridge body. The gaskets also provide a sealing surface adjacent the inlet of the valve cartridge. However, a force exerted on the gaskets is transferred to the ceramic discs which makes it difficult to predict and control the force exerted on the discs when the cartridge is inserted into a faucet casting. Additionally, the gaskets may expand under certain conditions which would increase the force exerted on the ceramic discs. Further, the gaskets may harden and crack which may lead leaking and loss of the gasket's resilience. When the gasket looses resilience it will not adequately secure the ceramic discs within the valve body.